1. Field of the Invention
The present invention relates to a latch bolt mechanism of a tubular lock that is adjustable in backset by using an extension casing.
2. Description of the Related Art
Many devices have been proposed to allow adjustment in backset of a lockset such that the lockset can be used with either one of two kinds of backset configuration in the structure of traditional latch bolt mechanismxe2x80x94namely, a 2xe2x85x9c inch type and a 2xc2xe inch type. An example of backset-adjustable latch bolt mechanisms is disclosed in U.S. Pat. No. 4,711,477 issued to Fann et al. on Dec. 8, 1987. The present invention is intended to provide a different design in this regard.
It is an object of the present invention to provide a latch bolt mechanism of a tubular lock that is adjustable in backset in response to the user""s need by using an extension casing.
A latch bolt mechanism of a tubular lock in accordance with the present invention allows adjustment in backset by using an extension casing. The latch bolt mechanism has a latch bolt housing having a latch bolt mounted therein, the latch bolt being movable beyond a face plate or retracted into the face plate. Two plates are connected together and mounted to an inner end of the latch bolt. The plates includes aligned two first positioning holes, aligned second positioning hole, and aligned openings. An actuating plate is mounted between the plates and includes an end operably connected to the latch bolt. The other end of the actuating plate includes two teeth each having a block formed thereon. The blocks are pressed against by a follower plate that also includes two teeth. When either tooth of the actuating plate or the follower plate is pressed against by a spindle of the lockset, the latch bolt is retracted. An extension casing is mounted around the plates and movable toward or away from the latch bolt housing. The extension casing includes a first hole and a second hole through which the spindle of the lockset is selectively extended.
Other objects, specific advantages, and novel features of the invention will become more apparent from the following detailed description and preferable embodiments when taken in conjunction with the accompanying drawings.